High frequency tube



I Aprill3, 1943.

' HIGH FREQUENCY TUBE Filed'Dec. 11, 1940 INVENTOA D. ,GOOD'CHILD 2,316,236

Patented Apr. 13, 1943 [TED STATES ENT' OFF [16E HIGH FREQUENCY TUBE Fr k. D la G od l L n o Eng and s-- signer to. International Standard, Electric, Corporation, New York, N. Y;

Application Decemberll, 1940, S'erialN-o. 369,522 In Great Britain June 4, 1940 2 Claims. (Cl. 250-275) This invention relates to the construction of electron discharge devices of the kind wherein electrons are projected through a hollow metal resonator to set up or maintain oscillations in the resonator. Devices of this kind are described for example in the copending U. S. application of J. H. Fremlin, Ser. No. 367,401, filed November 27, 1940, and in the U. S. patent to Llewellyn, No. 2,190,668, granted February 20, 1940.

In accordance with the invention there is provided an envelope comprising a metal part or sheath distinct from the resonator and encompassing the resonator and the beam forming electrodes, this metal part of sheath being disposed in thermally-conductive connection with the resonator. Preferably the envelope also includes a glass bulb portion in which are sealed the leading-in conductors for the electrodes. It is however possible to employ, instead of the glass bulb, a metal foot forming a closure for the metal sheath and having eyelets in which the conductors are sealed in insulated fashion.

In another aspect the discharge device of the invention comprises a hollow metal sheath forming part of the envelope, the sheath being shaped to accommodate electrodes for projecting electrons through the resonator, which electrodes are fixed to the resonator.

For the abstraction of energy from the resonator there may be provided a co-axial conductor pair projecting from one end of the resonator and a bushing in the sheath for receiving said conductor pair when the resonator is slid into the sheath.

The invention and particular aspects and embodiments thereof will be more fully described in connection wtih tubes of the kind described in the above-referred to copending application Ser. No. 367.401, but it will be appreciated that considerations similar to those to be discussed arise in other tubes of the general kind referred to above.

In the practical construction of a sealed-off discharge device having a coaxial tube resonator as described in the above-mentioned application it is found necessary to provide for the removal of heat generated inside the resonator. Another requirement is that the external dimension of the device along the axis of the electron beam be short in order to facilitate the setting-up of the necessary intense magnetic field along that axis with the aid of external pole-pieces.

If the resonator and the co-operating electrodes are enclosed in a glass bulb, the fulfillmg of these requirements is difficult or imposthe cathode sible. There is the'alternative possibility of making the resonator serve as the envelope, but this puts further restrictions on the design and construction of the resonator apart from the essential restrictions imposed by the electrical requirements.

The resonator is now arranged to slide into a metal sheath which can readily be artifically cooled to withdraw heat from the resonator and which also accommodates the beam forming electrodes.

An embodiment is shown in the accompanying drawing in which Fig. 1 is a perspective view of the device, Fig. 2 shows the resonator and Fig. 3 the beam forming and controlling struc ture considerably enlarged.

Referring to the drawing, the resonator F of Fig. 2 comprises co-axial tubes with closed ends and aligned slots along a central diameter as described in the above-mentioned co-pending application. The cathode structure of Fig. 3

comprises an indirectly heated flattened tubular cathode C, and a control grid G covered over the rear half of its periphery by a metal shield The cathode and grid extend between mica bridges M supported by rods R. This structure is mounted over the slot S in the outer wall of the resonator by welding the rods R to nonmagnetic metal bands N, the whole of the cathode structure lying between these bands. Alternative methods of attaching the cathode structure may be used, for example the bands may be omitted and metal rivets employed in the wall of the resonator. The resonator has but one opening in its outer wall, the electrons after passing through this opening and through the slots in the inner tube being collected on the outer wall.

The envelope comprises a metal sheath A preferably of copper sealed to a glass bulb G. The sheath A consists of a cylindrical portion to receive the resonator and a co-extensive channelled portion Al for the cathode and grid. The end sealed to the bulb is circular. The leads E from structure are connected to conductors sealed in the bulb and the envelope is exhausted at H.

The resonator is slid into the sheath A (before shaping the end of the bulb G) and is a tight fit in the cylindrical portion. The resonator includes an outgoing line or antenna L and a sleeve D is provided on the end plate of the sheath through which the wire projects. A suitable seal Q is provided at this point.

It is clear that, when the line L is inserted in sheath A and passed through sleeve D, it may form a concentric line therewith. An insulatin bushing of known form and not shown may be provided on line L for assuring such concentricity, as will be clear. Alternately, the resonator energy extraction means may include line L projecting concentrically through a conductive bushing, say integrally formed with outer portions of the resonator, thus forming a coaxial conductor output lead structure. It would thus be possible to insert the resonator unit in the sheath in one step-n0 further adjustment for output lead concentricity being needed.

Since the resonator lies in contact netic field to be applied across a short gap, as the pole-pieces can fit closely on to the copper tube on either side.

The construction shown also enables a mag- 20 therein.

with the sheath, heat can readily be removed from it by, 15

' claim 1 in which said cathode means comprise Various modifications within the scope of the appended claims will be readily appreciated.

What is claimed is:

1. An electron discharge device having an envelope comprising a substantially tubular shaped metal sleeve with a glass bulb portion secured thereto, a hollow metal resonator disposed within said sleeve in contact with the greater part of the interior thereof for cooling said resonator, a slot formed in one side of said resonator, a channel formed in said sleeve overlying said slot and cathode means disposed within said channel and overlying said slotfor projecting a stream of electrons through said slot into said resonator.

2. An electron discharge device according to an indirectly heated flattened member and a control grid,ssaid means being mounted on the outer wall of said resonator in alignment with the slot FRANK DOUGLAS GOODCHILD. 

